Polycarbonates are generally produced using starting materials induced from petroleum resources. In recent years, however, there is a fear about depletion of petroleum resources, and it is desired to supply a polycarbonate produced using a starting material obtained from biomass resources, e.g., plants. Furthermore, since there is a fear about a possibility that the global warming due to the increase in carbon dioxide emission and to the accumulation of carbon dioxide might bring about climate changes, etc., it is desired to develop a polycarbonate which is produced from a plant-derived monomer as a starting material and which is carbon-neutral even when discarded after use.
Hitherto, various polycarbonates produced from plant-derived monomers as starting materials have been developed.
For example, a technique has been proposed in which isosorbide is used as a plant-derived monomer to obtain a polycarbonate through transesterification with diphenyl carbonate (see, for example, patent document 1). A polycarbonate obtained through copolymerization with bisphenol A has been proposed as a copolycarbonate obtained by copolymerizing isosorbide and another dihydroxy compound (see, for example, patent document 2). Furthermore, an attempt has been made to copolymerize isosorbide and an aliphatic diol to thereby mitigate the stiffness of the homo-polycarbonate obtained from isosorbide (see, for example, patent document 3).
Meanwhile, a polycarbonate obtained by polymerizing 1,4-cyclohexanedimethanol, which is an alicyclic dihydroxy compound (see, for example, patent documents 4 and 5) and a polycarbonate produced by adding a rubbery polymer to a polycarbonate obtained by the transesterification of isosorbide with diphenyl carbonate (see, for example, patent document 6) have also been proposed.
Moreover, a polycarbonate produced by adding a styrene-based resin to a polycarbonate obtained by the transesterification of isosorbide with diphenyl carbonate has been proposed (see patent document 7).